Removal of wax from hydrocarbon oils



Patented Nov. 1, 1932 UNITED STATES- PATENT OFFICE HUGH LOWERY, OJi ALTON, ILLINOIS, ASSIGNOR' TO STANDARD OIL COMIEANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS REMOVAL OF WAX FROM HYDROCARBON OILS No Drawing.

This invention relates to the removal of wax from-hydrocarbon oils and particularly lubricating oils containing slop wax, that is wax of properties and molecular weight intermediate those of paraffin wax and petrolatum.

The lubricating oil to be treated may be a heavy lubricating distillate constituted by the cut between 80% and 90% oil on Mid- Continent crude. Such a cut has a viscosity between 75 and 120 seconds Saybolt at 210 F. The invention is not intended to be limited to the treatment of this particular cut since it is applicable-to any hydrocarbon distillate containing substantial quantities of slop wax.

When such a wax-containing distillate is diluted with naphtha or other suitable diluent and allowed to settle at low temperatures,

the separation of wax and oil is very unsatisfactory since only a relatively small quantity of oil can be recovered. I have now discovered that if a relatively small quantity of petrolatum is added to the diluted oil,

the separation is greatly improved and much greater yields of lubricating oils are obtained.

The invention will be more readily understood from the following specific example:

A distillate containing slop wax, constituted by the cut between 84% OE and 87% oil from Mid-Continent crude, having a viscosity of about 90 seconds Saybolt at 210 F solid between 80 F. to 110 F. and containing between 7 to 12% of wax of the slop Wax type is diluted with about 70% of naphtha of about 400 F. end point. A small amount, for example, between 1 and 5% of petrolatum derived from steam refined cylinder 4 stock by settling or centrifuging, having a melting point between 120 and 160 F. and containing between 30 and 70% of .oil, is added to the-naphtha solution. The solution is now slowly chilled to 10 F. and maintained at that temperature for between 60 and 80 hours. During this time thewax settlesout leaving a supernatant layer of clear oil amounting to between 70 and 80% of the whole. After removing the naphtha the oil has a pour point of about 40 F.

Application filed October 27, 1928. Serial No. 315,597.

By way of comparison it may be stated that if the petrolatum is omitted only about 20 or 25% of clear supernatant oil separates under the same conditions and no variation of the amount of diluent, time or temperature, of settling improves that result.

The settled oil is reduced to remove the diluent and can be acid treated and finished in the usual way. For example, the oil may be treated with sulfuric acid, clayed and further wax may be removed therefrom if desired.

The distillate from which wax is to be removed may be treated and clayed to color before settling. 'In this case the petrolatum used may be first purified to approximately the same color as the oil to avoid contamination of the latter. This purification may suitably be effected byfiltering the petrolatum through clay.

Althoughthe present invention has been described in connection with the details of a specific embodiment thereof, it is not intended that such details shall be regarded as limitations upon the scope of the invention, except in so far as included in the accompanying claims.

I claim: 1

l. The method of removing slop wax from. hydrocarbon oils containing same which consists in diluting such oil with a relatively low boiling hydrocarbon oil, adding a small quantity of petrolatum thereto, chilling and allowing the wax to separate from the 011.

2. The method of dewaxing a petroleum oil lubricating distillate containing wax of the slop wax type, which consists in adding a light diluent to said distillate to reduce the viscosity and to thereby facilitate the settlement of wax, adding between about 1 and 5% of petrolatum wax,.chilling to a low temperature and allowing the wax to settle out.

3. In the process of-removlng slop wax from hydrocarbon distillates containing such wax by diluting, chilling and settling, the step of adding a small quantity of petrolatum, thereto before I said chilling and'settling.

4. The method of dewaxing a petroleum oil lubricating distillate having a viscosity between 75 and 120 seconds Saybolt at 210 F. 100

and containing wax of the slop wax type which consists in diluting said distillate with between 65 and 80 of a naphtha of end point not substantially over 400 F., adding be- 5 tween about land 5% of petrolatum, chilling to about F., allowing to settle at such temperature for 60 to 80 hours, and removing the supernatant layer of oil.-

In testimony whereof I have hereunto set 10 my hand and seal, this 24th day of October,

- HUGH LOWERY; 

